Double-diaphragm pump



Y March 17, 1959 H. E. RlTTENHoUsE 2,877,715.

l DOUBLE-DIAPHRAGM PUMP Filed July 1:5, 1954 rlcl HmHHHMU@ United States Patent Oce 2,877,715 Patented Mar. 17, 1959 DOUBLE-DIAPHRAGM PUMP Howard E. Rittenhouse, Fort Wayne, Ind., assignor to Tokheim Corporation, Fort Wayne, Ind., a corporation of IndianaV Application July 13, 1954, Serial No. 443,121

17 Claims. (Cl. 103-150) double-diaphragm pump having two diaphragms with self-sustaining or permanently arched working portions and in which the arched working portions are stressed in tension on their discharge strokes and in compression on their suction strokes. It is an object of the inventionto provide a pump in which the displacement chambers vswept by the two diaphragms have small clearance volumes at the ends of the stroke, w'hich has a high displacement ratio and a high suction lift and produces a high discharge head, and in which either full or partial strokes produce effective and positive pumping with no l'ost motion and with no introversion of the diaphragm walls.

ln accordance with the invention, a single pump body forms two casing wal-ls mounted back-to-back on opposite sides of a central support which forms inlet and outlet passages for the two casings and which forms a central bearing for a reciprocating pump rod. The passagedening walls provide diametrically extending reinforcements yfor the body. Each casing is generally in the form ot a circular plate which carries a diaphragm support at its periphery, desirably in the form of a cylindrical rim.

Coaxial valve bores through the central portions of the casing Walls communicate respectively with the inlet and outlet passages, and valves are desirably provided by valve assemblies pressed into such bores. The reciprocating pump rod carries a central piston inoperative aslsociation with each casing, and a diaphragm working portion is supported from, and spans the space between,

the edge of each piston and'the peripheral diaphragm support of its associated casing. v

Each diaphragm working portion is desirably formed -in cross-section and supported as a self-sustaining or permanent arch, and the opposite wall of the casing is desirably formed to mate with the inward face of the arched wa'll at the inner end of its stroke. While the convex face of the arched wall can be presented inwardly, and the opposite casing wall made concave, I prefer to arch the wall outward so that its concave face is presented toward the casing wall, and to make that casing wall convex to mate with the concave diaphragm face. The casing wall opposite the central piston of each diaphragm is desirably at to mate with the flat piston at the inner end of the stroke. The pump is preferably supported at one or both ends of its diametrical reinforced portion, and may be operated in any suitable way, conveniently by a manually operable lever connected to the pump rod and pivoted on a yoke supported at the ends of the reinforced portion.

The accompanying drawing illustrates the invention. In such drawing:

Fig. 1 is a vertical axial section of a pump embodying my invention;

Fig. 2 is a front elevation of the pump shown in Fig. l; and

Fig. 3 is a central vertical section taken on the line 3 3 of Fig. 1'.

The pump shown in the drawing comprises a single pump body 10 having two spaced and generally circular casing walls 12 and 14, joined by a central bearing boss 16 and by the walls of an inlet passage 18 and an outlet passage 20. The central structure between the two walls may also include a nozzle hanger 22. The outer face of each wall 12 and 14 carries at its edge an annular enlargement having a generally cylindrical peripheral face 24 to support the outer edge of a diaphragm. Such outer face 24 is desirably provided with a groove 26 in which the diaphragm may be clamped by a clamping ring 28. The cylindrical face 24 of each enlargement merges with an axially outwardly arched or convex wall 30, positioned to lie opposite the working annulus of the diaphragm. The annular enlargements may be provided with circumferenltia'lly spaced notches 31 to provide radial communication passages in the displacement chambers.

The central portion 32 of each wall 12 and 14, within vthe annular enlargement, is generally flat to mate with the central piston portion of the diaphragm structure, and

lmay be provided with an annular groove 34 to receive the flange at the edge of that piston portion. The lower end of the body 1t) forms a tting 36 to receive an inlet pipe 37 and to support the pump thereon, and the top of -the body forms an outlet iitting 38 to receive a discharge pipe 39. v

Within the iiat central area ofI each Wall 12 and 14,

pressed. Each valve assembly comprises a cylindrical casing 48 having an end wall 49 which forms a valve port 50 anda surrounding valve seat 52. A valve disk 54 is loosely received wit-hin the casing 48 and is biased to closed position by a light spring 56 reacting against an apertured end wall 58 at the opposite end of the valve casing. The assemblies 44 which communicate with the inlet passage 18 are arranged to open from that inlet passage, while the valve assemblies 46 which communicate with the outlet passage 20 are arranged to open toward that outlet passage 20.

A pump rod 60 is slidably received in the central bearing boss 16. At its rear end (to the 4right in Fig. l) it carries a pair of disks 62 clamped againstl the central circular portion of the rear diaphragm 84 to form a central piston 64 for the diaphragm structure. Adjacent its -front end, the pump rod 60 carries a similar pair of disks -62 clamped against the central portion of the front diaphragm 82 to form a similar piston 64. The forward end `61 of the pump rod 60 is pivotally connected to a handle 'lever 66 carried by a relatively iixed pivot pin 68, The pivot pin 68 is carried by a yoke 70 which spans the pump body and whose opposite ends are apertured and lreceived over the ttngs 36 and 38 at the opposite ends of the pump body 10.

Each diaphragm 82 and 84 has a at central portion clamped between the plates 62 and exibly connected to the inner periphery of an annular working portion 80.

lThe outer edge of the working portion is flexibly yarched configuration.

manent arch. While the arch support can be provided in other ways, it is desirably provided by the material of the diaphragm itself, by making that wall sufiiciently rigid to maintain the arched configuration under the collapsing forces imposed on it during the operation of the pump. Preferably, the arched working annulus 80 is relatively thick and rigid at its central portion, that is, at the apex of the arch, and progressively thinner and more fiexible toward its inner and outer peripheries where it is flexibly connected to the central portion and the edge portion of the diaphragmas described and claimed in Patent No. 2,685,304. Each diaphragm is desirably molded to a normal shape with the working annulus in It is desirably made of a rubber or other material which is inert and impervious to the fluid to be pumped. It should be flexible, especially at the edges of the working annulus, but preferably has little elasticity or stretch, and it may be reinforced against elongation, as with embedded fabric. For certain uses, as for pumping gasoline and fuel oil under low tem- -perature conditions, the diaphragm may be made of leather.

The pump body can be made as a single casing, preferably a die casting, and requires a minimum of finishing operations. With a suitable casting, it is only necessary to thread the collars 36 and 38 for the reception of the inlet and outlet pipes, to finish the bore of .the bearing boss 16, and to finish the bores 40 and 42 for the press-fit reception of the valve assemblies 44 and 46. Since the bores 40 for the two sides of the pump are aligned and the bores 42 are similarly aligned, each pair of bores 40 and 42 can be finished in a single boring pass through the body 10. The walls of the passages 18 and 20, with the bearing boss 16, reinforce a diametrical section of the pump body, which extends between the fittings by which the pump is ordinarily supported and on which the lever-supporting yoke is carried.

For use, the pump may be supported by the inlet pipe 37 or by the two pipes 37 and 39, and is operated by reciprocation of the handle lever 66 to reciprocate the two diaphragms through opposite strokes, as between the extreme positions shown in full and dotted lines in Fig. 1. When the central piston 64 of a diaphragm is at the inner end of its stroke, it substantially conforms to the flat central portion 32 of its associated casing wall, and the arched working annulus of the diaphragm is drawn into substantially mating contact with the convex face 30 of the annular enlargement carried by that wall. As the piston 64 of the diaphragm s moved outward, the arched working annulus pivots bodily in arched form about the outer portion of the convex face 30 of the casing wall. The arch support maintains the working annulus in arched form, with the span of the arch varying as the distance between its inner and outer supports changes with the axial movement of the central piston 64. In each case, the outward movement of the diaphragm occurs on the suction stroke, and during this stroke the arched wall of the working annulus is stressed in compression, that is, the force on that arched wall tends to collapse the arch. But because of the support for the arch, no collapse or introversion occurs, and the entire movement of the diaphragm produces effective pumping and draws fluid into the displacement chamber through its inlet valve 44.

Upon the opposite or discharge stroke, as from the full line position of the diaphragm 84 to its dotted line position shown in Fig. l, the arched diaphragm wall is stressed in tension, and because of its deeply arched configuration, it takes substantially the form of a catenary in which the tension stress is substantially minimum. The inward or discharge stroke discharges fluid from the displacement chamber through the outlet valve 46 to the passage 20.

At the inner end of the stroke of each diaphragm, its

central piston portion and arched working annulus lie in substantially mating relationship with the casing wall, and the clearance volume is substantially a minimum. Because of this, and of the positioning of the valves 44 and 46 close to the displacement chambers, the displacement ratio of the pump is high, that is, the ratio of the swept volume to the total volume is high, and the pump will have a high suction lift.

I claim as my invention:

l. A diaphragm pump, comprising a pair of oppositely disposed casing walls, a diaphragm operatively associated with each wall to define a pump displacement chamber between itself and the wall, each diaphragm having a rigid central piston portion and a working annulus extending between and supported by the piston portion and an outwardly spaced peripheral support on the associated wall, valved inlet and outlet passages communicating with the displacement chambers, pump-actuating means mechanically connected to said piston portions for jointly reciprocating said piston portions through opposite strokes, supporting means sustaining the working annulus of each diaphragm in arched cross-section between the piston portion and the outer peripheral support of the diaphragm with the concave face of the annulus presented toward its associated casing wall, whereby both arched working annuli are stressed in compression on the suction strokes of their diaphragms.

2. A diaphragm pump as defined in claim 1, in which the annular portion of each casing wall opposite its diaphragm working annulus is formed with a convex face which substantially mates with the arched working annulus at the end of the stroke toward such wall.

3. A double-acting, double diaphragm pump, comprising a pair of spaced casing walls supported in back-toback relationship, a diaphragm operatively associated with each wall with its outer periphery secured thereto to form a pump displacement chamber between itself and the outer face of the wall, each diaphragm having a rigid central piston portion and a working annulus which is self-supporting in permanently arched configuration and extends from said piston portion to the supported outer periphery of the diaphragm, inlet and outlet passages communicating with the two displacement chambers through the two walls, and a pump rod supported with said walls for reciprocation centrally therethrough and connected to reciprocate jointly the central portions of said diaphragms.

4. A diaphragm pump as defined in claim 3 in which each arched working annulus merges at its outer periphery into a cylindrical outer portion, each casing Wall having an outer cylindrical face receiving the said outer portion of 'its associated diaphragm, and tension means overlying and securing the said outer portion to the cylindrical face.

5. A diaphragm pump as defined in claim 3 in which the arched working annulus of each diaphragm is outwardly arched to present its concave face toward its displacement chamber, whereby the arched wall is stressed in compression on its suction stroke.

6. A diaphragm pump as defined in claim 5 in which the casing wall opposite each outwardly arched working annulus has a convex annular face which substantially mates with the concave face of the arched working annulus at the inner end of its stroke movement.

7. A diaphragm pump, comprising a casing body forming a pair of spaced casing wals, a pump-rod bearing in said casing body and forming a pump-rod opening centrally through the casing body, interconnecting structure extending between the walls and therewith forming diametrically opposite inlet and outlet passages between the walls, inlet and outlet fittings communicating with said passages and projecting beyond the edges of the casing ment chambers between themselves and the outer faces in communication respectively with the inlet and outlet passages, and valve assemblies are mounted in said valve bores.

9. A mechanically-actuated, double-acting double-diaphragm packingless pump, comprising a central pumpcasing, opposite end walls thereon defining the inner walls of opposite displacement chambers, inlet and outlet valves and passages communicating with said chambers through said walls, a diaphragm secured against each casing end wall as the end wall of the pump, each diaphragm having an outer peripheral portion sealed to its adjacent casing end wall and having a central `piston portion, apump rod slidably mounted through said casing connecting the diaphragm piston portions for joint reciprocation through oppostely acting pump strokes, and pump-actuating means mechanically attached externally to the piston portion of one diaphragm for jointly reciprocating both diaphragms, the pump chambers being wholly closed by said body and diaphragms and said one diaphragm acting as a packingless seal bewteen the pump-actuating means and the double diaphragm pump.

10. A pump diaphragm, comprising a working annulus extending in arched cross-section between its inner and outer peripheries and adapted to undergo relative axial reciprocation of its inner and outer peripheries, said annulus having a relatively rigid apex portion merging with a relatively more flexible arch-base portion, the outer arch wall merging in a continuous curve with a generally cylindrical attachment wall, the said arched cross-section being self-sustaining in arched configuration and said merging connection with said cylindrical wall providing a support which transmits substantially in its own plane reaction stress from loads against the faces of the selfsustaining arched annulus. t

ll. A diaphragm pump, comprising a rigid wall delining the inner face of a displacement chamber, the outer annular area thereof being of convex cross section merging into an outer cylindrical face at the periphery thereof, a diaphragm having an outer cylindrical wall received against said cylindrical face and merginglyv joined to a working annulus overlying said convex annular area, means supporting the inner periphery of said annulus for relative axial stroke reciprocation with respect to said outer cylindrical wall, said working annulus being of arched cross section adapted to substantially mate with said convex annular face area at the inner end of said stroke reciprocation and being self-sustaining in such arched configuration throughout said stroke reciprocation, the arched annulus being stressed in compression on the suction stroke thereof and in tension on the discharge stroke thereof, the joining of said diaphragm working annulus to said diaphragm cylindrical wall being in a smooth curve whereby reaction to said compression and tension stress is transmitted to said cylindrical Wall substantially in the plane of said diaphragm.

12. A mechanically-actuated double-acting doublediaphra-gm packingless pump, comprising a central pump body having its opposite end faces formed to define the inner faces of opposite displacement chambers, valved inlet and outlet passages communicating with said chambers through said faces, a diaphragm secured to the body over each end face to form a displacement chamber therewith, each diaphragm having an outer peripheral portion sealed to the body and having a central piston portion, a pump rod slidably mounted through said body connecting the diaphragm piston portions for joint reciprocation through oppostely acting pump strokes, and pumpactuating means mechanically attached externally to the piston portion of one diaphragm for jointly reciprocating both diaphragms, the pump chambers being wholly closed by said body and diaphragms and said one diaphragm acting as a packingless seal between the pump-actuating means and the double-diaphragm pump.

13. A mechanically-actuated double-acting doublediaphragm packingless pump, comprising a central pump body having its opposite end faces formed to define the inner faces of opposite displacement chambers, valved inlet and outlet passages communicating with said chambers through said faces, a diaphragm secured to the body over each end face to form a displacement chamber therewith, each diaphragm having an outer peripheral portion sealed to the body and having a central piston portion, a pump rod slidably mounted through said body connecting the `diaphragm piston portions for joint reciprocation through oppostely acting pump strokes, a rigid Asupport member supported from said central body and extending over `one of said diaphragms externallythereof, and a manually operable pump lever pivotally supported by said support member and mechanically attached to the piston portion of lsaid one diaphragm for jointly reciprocating both diaphragms, said one diaphragm acting as a packingless seal between the pump-actuating means and the double-diaphragm pump.

14. A double-acting double-diaphragm pump, comprising a central pump body having its opposite end faces formed to define the inner faces of opposite displacement chambers, inlet and outlet passages in said body communieating with said chambers through said faces, a diaphragm secured to the body over each end face to form a displacement chamber therewith, each diaphragm having an outer peripheral portion sealed to the body and having a stitfened central portion, a pump rod slidably mounted through said body connecting the stiteued central portions for joint reciprocation through oppostely acting pumping strokes and maintaining the same in predetermined spaced relation, manually operable lever means connected externally to said interconnected stiffened portions for jointly reciprocating both diaphragms, the predetermined spacing -between said stitfened portions being limited in relation to the thickness of said pump body between the same, the stitfened portion of each diaphragm on its inward stroke moving against the pump body as a stop limiting both its own inward stroke andthe outward stroke of the opposite diaphragm.

l5. A double-acting double-diaphragm pump, comprising a central pump body havin-g opposite end faces defning the inner faces of opposite displacement chambers, radially outer portions of said end faces being formed by walls which lie in spaced back-tobackrelation, a diaphragm support on each said wall peripherally of the end face thereof, interconnecting walls joining the backs of said spaced walls and supporting said diaphragm supports, said interconnecting walls and spaced walls defning inlet and outlet passages between said spaced walls, the body-defined faces of said displacement chambers being provided with openings therethrough connecting the chambers to said passages, a diaphragm supported on each diaphragm support and forming a displacement chamber with an end face of the body, means interconnecting the diaphragms for joint reciprobation through oppostely acting pump strokes, and actuating means supported from said body and mechanically connected externally to said interconnected diaphragms to actuate the same.

16. A double-acting double-diaphragm pump, comprising a central pump body having opposite end faces defining the inner faces of opposite displacement chambers, radially outer portions of said end faces being formed by walls which lie in spaced back-to-back relation, a diaphragm support on each said wall peripherally of the end face thereof, interconnecting walls joining the backs of said spaced walls and extending to the periphery thereof, said interconnecting and spaced walls forming a reinforced body portion and dening therein flow passage means communicating with the displacement chambers through the body-defined faces of the same, means for mounting said body by said reinforced body portion, a diaphragm supported on each diaphragm support and forming a displacement chamber with an end face of the body, means interconnecting the diaphragrns for joint reciprocation through oppositely acting pump strokes, and actuating means supported from said Ibody and mechanically connected externally to said interconnected diaphragms to actuate the same.

17. A double-acting double-diaphragm pump, comprising la central pump body having opposite end faces defining the inner faces of opposite displacement chambers, radially outer portions of said end faces being formed by walls which lie in spaced back-to-back relation, a diaphragm support on each said wall peripherally of the end face thereof, interconnecting walls joining the backs of said spaced walls and supporting said diaphragm supports, inlet and outlet passages communicating with said displacement chambers through the body-defined faces thereof, means to connect the outlet passage to a hose, said interconnecting walls also forming a hose nozzle support, a diaphragm supported on each diaphragm support and forming a displacement chamber with an end face of the body, means interconnecting the diaphragms for joint reciprocation through oppositely acting pump strokes, `and actuating means supported from said body and mechanically connected externally to said interconnected diaphragms to actuate the same.

References Cited in the le of this patent UNITED STATES PATENTS 1,920,014 Horton July 25, 1933 2,258,009 Horton Oct. 7, 1941 FOREIGN PATENTS 346,756 France Dec. 9, 1904 480,675 Great Britain Feb. 22, 1938 481,270 Great Britain Mar. 8, 1938 

